DAY 398
A postman delivers one letter on his first day of work, three letters on his second day of work, five letters on the third day, and so on - delivering two letters more each day than he delivered the previous day. How many total letters has he delivered after fifteen days of work?
Answer:
225
DAY ................ NUMBER OF LETTERS DELIVERED
1 .................................................... 1
2 ................................................... 3
3 ................................................... 5
4 ................................................... 7
5 ................................................... 9
6 .................................................. 11
The total number of letters delivered is the square of the number of days worked. For example, after 4 days, he has delivered 1 + 3 + 5 + 7 = 16 letters.